Skid steer loaders are highly maneuverable self-propelled loaders which have lift arms that can be used to raise and lower loads at the front of the loaders. The loaders have operator compartments accessible from the front. The lift arms are pivoted at the rear of a main frame of the loader and extend forwardly along the sides of the operator compartment.
A pair of hydraulic lift cylinders are utilized for raising and lowering the lift arms. Each lift cylinder is pivotally mounted between a respective one of the lift arms and the main frame of the loader. Such lift cylinders are subject to damage when high impact loads are exerted on them during use. High impact loads can occur if the piston of the lift cylinder bottoms out against the head of the cylinder to stop a bucket that is dropped from its raised position, for instance. Other impact loads may be experienced by the lift cylinders when forward movement of the skid steer loader is abruptly stopped, as when driving a lowered bucket into the ground in an attempt to fill the bucket. In some prior skid steer loaders, a separate lift arm stop is mounted to each side of the main frame so as to engage a respective one of the lift arms when the lift arms are lowered to their lowered positions. Such stops prevent the lift cylinders from bottoming out, thus eliminating one source of impact loads on the lift cylinders.
Such skid steer loaders also have a front cross member that joins the lift arms immediately in front of the operator's compartment. The cross member is adjacent, but spaced from, a front wall of the loader main frame when the lift arms are in a lowered position. The cross member has to be rigid enough to serve the purpose of holding the lift arms together and to support one or a pair of hydraulic cylinders for tilting a front mounted bucket or other implement mounted to the lift arms. In some prior skid steer loaders, the cross member has been made wide enough to eliminate any gap between it and the front wall of the main frame so as to serve as a stepping surface when entering or exiting the operator compartment of the loader. However, it is also desirable to make the cross member as narrow as possible (in fore and aft direction), in order to help visibility of the load when the lift arms are raised during operation. A narrower lift arm cross member also reduces the amount of material accumulation on the cross member. Unfortunately, a narrow cross member reduces the stepping area for the operator and creates a gap between the front frame wall and the cross member into which the operator's foot might slip when entering or exiting the operator compartment.
The above problems have been addressed in the past by separate solutions. For instance, the two "needs" for the lift arm cross member present conflicting demands, namely keeping the cross member small for visibility improvement and reducing accumulation of material on the cross member, while on the other hand keeping the top wall of the cross member wide for good operator footing has been addressed in a manner shown in U.S. Pat. No. 5,078,568, which employs a strap step to fill the gap between the from frame member and the cross member when a narrow cross member is used. This structure, however, does not address the need to provide a lift arm stop to prevent damage to the lift cylinders of the loader. The combination step/stop of the present invention satisfies all of these diverse needs with an integral cooperative arrangement, which is simple and inexpensive to construct.